Environmental Characteristics of Smart Growth Neighborhoods

An Exploratory Case Study

The approach used in this exploratory case study included the following steps:

Definition of a "smart" neighborhood design. The 27 principles in the Charter of the Congress for the New Urbanism (CNU) provided a useful starting point in defining the type of new neighborhood design that we wanted to study. Among these, important characteristics included CNU's preference for "infill development over peripheral expansion," and compact designs that utilize transit, pedestrian, and bicycle systems to reduce auto dependence.

Selection of a study community. In consideration of this study's limited resources, it was determined that the study would be conducted in a community where Criterion already had ready access to local data. Given this, Sacramento, California was selected because of recent work performed by Criterion in the area.

Selection of a test project. The database of new urbanist projects maintained by the trade publication New Urban News was reviewed for completed projects in Sacramento, resulting in the selection of Metro Square, a residential infill project of 46 single-family detached dwellings that was completed in 1998. Metro Square's important "smart" features include its infill location one mile from the city center, and its high-density design of detached single-family dwellings (1,500-2,000 sq.ft. homes on 1,700 sq.ft. parcels) centered around a common open space. Appendix A contains photographs and maps of Metro Square.

Selection of conventional projects for comparison purposes. Two conventional residential projects were selected for comparison against Metro Square. Based on consultation with City of Sacramento staff, the North Natomas subdivision was selected as most representative of recent "conventional" residential development in the community, and 46 single-family parcels in that subdivision were designated for examination. The Natomas dwellings range from 2,000 to 2,500 sq.ft. on 7,400 sq.ft. parcels, and are situated approximately six miles from the city center. Natomas maps and photographs are presented in Appendix A. Because household-level travel demand data are not yet available for the Natomas subdivision, a second suburban development was selected to provide data from the most recent regional travel survey, conducted in 1991. Based on consultation with Sacramento Area Council of Governments staff, the Antelope subdivision was selected because of the availability of household travel diary surveys for that area. A 46-parcel segment of the subdivision was designated for examination, with single-family dwellings of 1 "Infrastructure construction-embodied energy use" is used to describe the energy that was used in construction when infrastructure was built. 1,800 to 2,000 sq.ft. on 6,000 sq.ft. lots. Antelope is situated approximately 11 miles from the Sacramento city center. Antelope maps and photography are given in Appendix A. Figure 1 (pdf, 24k) shows the location of all three sites in relation to the Sacramento city center and city limits. It should be noted that the conventional projects were selected to match the number of households at Metro Square, but not necessarily the size, income, or auto ownership characteristics of those households.

Identification of applicable environmental impacts. A comprehensive set of environmental issues that could theoretically be affected by neighborhood design were identified, as shown in Table 1. Of this universe of environmental topics, those most relevant to the three study sites were determined to include:

Measurement of environmental indicators where feasible. Local databases covering the three sites were then examined to determine data availability for the relevant environmental issues. The objective was quantitative measurement of the sites using a set of indicators where data were available to support such measurement. To organize this task, the environmental measurements were divided into two general groups: 1) those indicators addressing the built environments of the sites; and 2) those indicators addressing the travel demands of the sites.